M103's are ok
M104's are faster
93-95 has issues with bad wiring harness
Find out if it has had the head gasket done, new head gasket has mod to address original design fault.
Avoid 4 Matic and ASR equipped models as orig ASR was POS and MB parts for the early 4 Matic are pricey.

My daily ride is a 93 300E sportline M104 with 170k on the clock.
18-20 mpg in town
28-30 mpg on the highway